(1) Field of the Invention
The present invention relates to an oil leakage detector and an oil leakage detection method, and particularly to an oil leakage detector and an oil leakage detection method suitable for detection of an oil leakage in an oil-filled device such as a transformer, a condenser, a hydraulic operation device for GIS (gas insulated switchgear), a rectifier or the like.
(2) Description of the Related Art
There has heretofore been a concern for an oil storage tank or a transformer or the like to cause a leakage of oil (oil leakage) due to deterioration or an accident or the like. Since the oil leakage may lead to environment pollution and disasters, there has been a demand for a simple and highly-accurate detection technology in an early stage of the oil leakage.
As a related art technology for addressing this problem, there are known those described in Patent Documents 1 and 2.
Japanese Patent Application Laid-Open Publication No. 2008-116389 (Patent Document 1) describes that when ultra-violet light including an absorption wavelength of leakage oil is irradiated on an object to be measured from outside, fluorescence emitted from the leakage oil is detected, and that the accuracy of detection of fluorescence is enhanced by using a filter through which a visible light component of ultra-violet light (black light) does not pass, and a bandpass filter which allows the center wavelength of the fluorescence to pass therethrough.
Further, Japanese Patent Application Laid-Open Publication No. 201.3-101474 (Patent Document 2) describes that the presence or absence of oil is determined based on the intensity of a predetermined specific color in colors at respective pixels of a color image of colored leakage oil.
In the technology described in Patent Document 1, however, the intensity of fluorescence which reaches a detector was reduced with the use of the bandpass filter. For example, it was difficult for the technology to detect a small amount of leakage oil adhered to the surface of a transformer. Further, the technology was accompanied by a problem that the structure of the detector was complicated when using an optical filter.
On the other hand, there has been a demand for the technology described in Patent Document 2 to establish a detection technology which is simple, e.g., filterless, and capable of also detecting a leakage of colorless oil because it is not possible to detect the colorless leakage oil.
The present invention has been made in view of the foregoing. An object of the present invention is to provide an oil leakage detector and an oil leakage detection method both high in detection accuracy, which are capable of also detecting colorless oil without complicating the oil leakage detector.